Really? what else are they good for? Sport shooting? They are fun to shot at a range? I wanna see if my CQM and CQB are to standard?

Yes...all of those things. Plinking, competition, hunting, home defense. They're good all-around long guns with a wider variety of applications than most. Easy to shoot, low recoil, easy to modify, wide variety of accessories. They're reliable, durable, and low maintenance (some brands more than others). Not an accident that they are by far the best-selling long gun of the last decade or two.